Composite reinforced wood structural members

ABSTRACT

A wood pole having a wood body defined by a stripped tree trunk is reinforced by strips of composite reinforcement wrapped helically around the wood body, wherein the reinforcement comprises parallel high strength filaments in a resin matrix. The thickness and/or number of layers of reinforcement can be varied along the length of the pole to best suit the loading to which the pole is to be subjected. The reinforcement also performs the functions of the prevention of rot, insect infestation and water absorption, which are conventionally performed by harmful materials such as creosote. An electrical conductor can extend the length of the pole, protected under the reinforcement, which is transparent to electromagnetic signals, to act as an antenna or as a ground wire. No-maintenance color, fire retardant and/or reflective elements can be mixed in with the resin during the reinforcing of the pole.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority of U.S. Provisional PatentApplication No. 60/176,056, filed Feb. 3, 2000, which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to wood structural members and,more particularly, to elongate, composite reinforced wood structuralmembers for uses such as utility poles, piles and beams.

[0003] In the United States alone, there are more than 100 millionelectric distribution poles and about 8 million to 10 million electrictransmission poles. The distribution poles are typically 45 feet to 50feet in length, whereas new transmission poles are usually from 85 feetto 100 feet in length and carry high voltage lines. Wood is, by far, thematerial of which most of these utility poles are made, although someare made of steel, concrete and composites. In order to make woodutility poles, trees are cut, delimbed and then peeled to the propertaper.

[0004] It is estimated that more than 250,000 transmission poles and 3million to 4 million distribution poles need to be replaced every year.Rot that occurs at the ground line and woodpeckers destroy many woodpoles or make them too weak for further service, and wind and ice stormscan destroy all types of utility poles. In some places, the life of awood utility pole can be as low as 10 to 15 years. The severe ice stormsin the northeastern United States and in the Canadian provinces ofOntario and Quebec in January, 1998, destroyed or damaged many thousandsof utility poles, including about 50,000 utility poles in Ontario andQuebec. In conditions like those of an ice storm, the weight of ice onlines and poles puts at least close to a maximum load on the poles. Ifone pole fails under such conditions, it very likely pulls downneighboring poles in a domino effect, thereby resulting in extensivedamage.

[0005] Wood utility poles are less expensive than utility poles made ofother materials. Composites are 5 to 10 times the cost of wood indistribution pole length sizes. As a result, many prime trees are cutdown to satisfy the need for utility poles. Over the years, most woodutility poles have been made from trees of the following types: westernred cedar, lodgepole pine, red pine, jack pine, Scots pine, southernyellow pine, Douglas fir and radiata pine. Softwood trees, such assouthern yellow pine, have a quick growth rate but lack durability.Scrub trees and other trees are unsuitable because they are too weak.Species such as hemlock and spruce do not absorb the materials normallyused to prevent infestation and rot. Therefore, they are not used asutility poles. The materials normally used to prevent infestation androt include such hazardous materials as pentachlorophenol, chromatecopper arsenate, ammoniacal copper arsenate, copper naphthenate andcreosote wood preservatives. The carcinogenic aspect of creosotedutility poles has been widely discussed, and in many cases creosotedpoles must be disposed of in separate land fills due to potentialcontamination from the creosote. Furthermore, because wood utility polesare made from trees, and trees have limbs, the bases of the limbs(commonly referred to as “knots”) become stress raisers in the poles. Inthe examination of many utility pole failures, it has been found thatthe failure originated at a knot area, usually about one third of theway up the pole. Wood utility poles are relatively inflexible andusually fail along a plane extending down at an angle from one side ofthe pole to the center, with the wood on one side of the plane pivotingaway from the wood on the opposite side of the plane. In addition, insome conditions, wood utility poles become saturated with moisture andcause ground shorting, in which current flows from lines carried by thepole through the pole to the ground. Saturation also leads to rottingand failure.

[0006] SUMMARY OF THE INVENTION

[0007] By the present invention, elongate structural members made ofwood, such as wood utility poles; can be reinforced with a compositematerial and thereby made stronger by a factor of from about 2 to about4, depending on the specific arrangement of the composite material.Reinforced wood utility poles and other reinforced elongate woodstructural members according to the present invention can comprise anelongate wood body defined solely by a core of a tree trunk. Thecomposite reinforcement increases the flexural strength of woodstructural members and gives them greater ductility. As a result, woodstructural members reinforced according to the present invention bendfarther without failing than bare wood structural members do.Furthermore, elongate wood structural members reinforced according tothe present invention have sufficient strength to perform their intendedfunctions, even though the wood bodies have insufficient strength inthemselves to perform the functions. Wood utility poles or other woodmembers of a given cross sectional area can be made much stronger, orwood poles or other wood members of a smaller cross sectional area canbe made strong enough to function as utility poles. Poles of lesserstrength classes can be strengthened to the strengths of higher strengthclasses. The utility industry defines various classes of utility poles,with varying amounts of strength required for each class in accordancewith the job that a pole must perform. Furthermore, poles from trees ofinferior species, that is, species of soft woods and species otherwisetoo weak to be used as utility poles previously, can be reinforced to besuitable for utility poles, thereby saving the trees of more valuablespecies. It is even contemplated that palm trees reinforced according tothe present invention can be used as utility poles, especially whereother types of trees are not available.

[0008] The composite reinforcement according to the present inventionperforms the functions of the creosote and other treatment materials. Asa result, the present invention makes possible the use of thenon-absorbing woods as utility poles. By performing the functions, suchas the prevention of rot and insect infestation and water absorption,previously provided by harmful materials such as pentachlorophenol andcreosote, the composite reinforcement eliminates the use of the harmfulmaterials and the associated contamination and disposal problems. Woodmembers reinforced according to the present invention can be totallywrapped by the reinforcement, including, in the case of utility poles,the areas where cross-arms are to be attached. In addition, a cap ofcomposite material can be placed on the top of the wood member. As aresult, moisture cannot get into the wood and cause the associatedproblems, such as rotting and ground shorting in the case of utilitypoles. Materials to discourage woodpeckers, such as cayenne pepper, canbe added to the resin during or prior to making of the reinforced pole.Known fire retardant materials, such as cayenne pepper, can be added tothe resin during the reinforcing of the poles so that the poles will beprotected against fire from brush fires and the like. Moreover, thereinforced structural members can be made in any color by adding colorto the resin component of the composite reinforcement as the structuralmembers are being wrapped. As a result, there is no need for painting ormaintenance. An outer winding of nylon, Reemay polyester or otherpolyester, or glass malts or veils, can be used to provide a significantlong-term barrier to degradation of the underlying compositereinforcement from ultraviolet light and other weather-related elements.Especially where the poles are to be installed close to vehiculartraffic, glass beads or other reflective elements can be mixed in withthe resin to be used in all or a portion of the outer layer ofreinforcement in order to provide greater visibility at night. As analternative, reflective tape can be placed around the pole under anouter covering of resin. The resin can be transparent, so that thereflective tape shines through the resin, while the resin protects thereflective tape from degradation. Furthermore, the high strengthfilaments of the reinforcement, such as glass fibers, and the resin canbe chosen to have the same index of refraction. As a result, thecomposite reinforcement is transparent, and the reflective tape canshine through one or more layers of the composite reinforcement. Thecomposite material also prevents ground shorting by acting as adielectric shell for wood utility poles. In this regard, E-type glassfibers, which are electrically non-conductive and transparent to radioand other electromagnetic signals, can be used as high tensile strengthfilaments in the composite reinforcement. Arrangements conventionallyused for attaching steps and cross-arms to wood utility poles can beused with reinforced utility poles according to present invention due tothe thinness of the composite reinforcement and the presence of thesolid wood core. Such arrangements cannot be used with totally compositeutility poles, which are typically hollow. Because the compositereinforcement provides so much strength, the present invention prevents,or at least greatly reduces, the failures of wood structural members dueto stress concentrations at knots. Composite reinforced wood utilitypoles according to the present invention can be smaller in diameter andgreater in height than unreinforced wood utility poles. Wood structuralmembers reinforced according to the present invention have higherflexural strength and greater ductility and can carry greater loads thanunreinforced wood structure members. Furthermore, by increasing ordecreasing the amount of the high tensile strength filaments in thecomposite which are oriented generally in the longitudinal direction ofthe wood structural members, the members can be made with greater orlesser stiffness, whatever is desired for a particular application.

[0009] The reinforced utility poles according to the present inventionare also well-suited to define the uprights and the horizontal member ormembers of towers for long distance energy transmission. H-towersconstructed with composite reinforced wood horizontal members, orcross-arms, and with the reinforced utility poles as uprights are lesscostly than conventional wood H-towers and yet have greater windresistance and ice load bearing ability.

[0010] The present invention can also be used for reinforced wood pilesfor piers and other marine applications. Unlike utility poles, the pilestypically are not tapered. However, some marine piles are tapered fromthe top to the bottom, the smaller end being pounded into the earth.

[0011] In addition to providing the advantages described above inconnection with composite reinforced utility poles, the compositereinforcement prevents the ends of the piles from splitting due topounding. In addition to poles having circular transversecross-sections, the present invention can be used with poles anduprights having non-circular transverse cross-sections, and with beamshaving non-circular or circular cross-sections. The wood structuralelements to be reinforced, whether uprights or beams, experience anincrease in shear modulus with the reinforcement according to thepresent invention.

[0012] In order to provide the above advantages, a wooden pole iscovered with one or more layers of a composite reinforcing materialcomprising a large plurality of parallel, continuous, lightweight, highstrength, electrically non-conductive nonmetallic fibers and a resinousmaterial encapsulating the fibers. The pole can be tapered from bottomto top, like a conventional utility pole. The pole can be the samediameter as a conventional utility pole, or can be smaller in diameterthan a conventional utility pole, since the composite reinforcingmaterial will provide the necessary strength. Because loads on a poleare significantly less at the top than at the bottom, the number oflayers of reinforcement can be decreased from the bottom to the topand/or the reinforcement can be otherwise arranged to provide thegreatest reinforcement for the areas of the pole that will be subjectedto the greatest stress. Because the utility poles are subject toside-to-side loads, as well as vertical compression, a large pluralityof parallel longitudinal fibers, as well as a large plurality ofparallel circumferential fibers, are in the composite reinforcement toprovide an adequate side-to-side load reinforcement. The compositereinforcement applied in accordance with the present invention preventsthe typical failure of the wood utility pole by hinged separation alonga plane extending down at an angle from one side of the pole to thecenter. It also changes the mode of failure to end-to-end tension shear,the overall result of which is a horizontal break. This change in themode of failure gives the reinforced wood utility poles greaterflexibility and greater toughness, increases the loads the poles canbear, and eliminates from pole failures the domino effect by whichneighboring utility poles fail as a result of the failure of a firstutility pole.

[0013] The present invention is well adapted to the use of utilitytransmission poles as antennas for cellular phones and for othernon-wired communications. By placing a conductor against a wood pole,running from the top to the bottom of the pole, a protected conductorcan be provided. Such a conductor can also be used as a grounding deviceto prevent stray current from short arcing across the insulators and totake any stray currents at the ground. The conductor can be placedeither in a groove cut longitudinally down the pole or simply on thesurface of the pole, in either case, prior to applying the compositereinforcement. The conductor can be in a straight vertical line, in aspiral around the pole, or in other configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The foregoing and other objects, aspects and advantages will bebetter understood from the following detailed description of a preferredembodiment of the invention with reference to the drawings, wherein:

[0015]FIG. 1 is a perspective view of an installed reinforced woodutility pole according to the present invention;

[0016]FIG. 2 is a front elevation of a reinforced wood utility poleaccording to the present invention before installation;

[0017]FIG. 3 shows a portion of a wooden core receiving first and secondlayers of composite reinforcing material and a conducting wire in themanufacture of a reinforced wood utility pole according to the presentinvention;

[0018]FIG. 4 is a transverse cross-section along the line 4-4 in FIG. 2;

[0019]FIG. 5 is a transverse cross-section of a reinforced utility poleaccording to the present invention having five layers of reinforcingmaterial;

[0020]FIG. 6 is a schematic showing of a portion of a strip of compositematerial having randomly oriented filaments for use in a reinforced woodutility pole according to the present invention;

[0021]FIG. 7 is an enlarged portion of a strip of compositereinforcement for use in a reinforced wood utility pole according to thepresent invention, wherein all filaments are parallel to the length ofthe strip;

[0022]FIG. 8 is an enlarged portion of a strip of compositereinforcement having an arrangement of filaments in the longitudinaldirection woven with filaments in the transverse direction;

[0023]FIG. 9 is an enlarged portion of a strip of compositereinforcement for use in a reinforced wood utility pole according to thepresent invention, wherein all of the filaments are transverse to thelength of the strip;

[0024]FIG. 10 is a load versus position curve for a bare wood testsample;

[0025]FIG. 11 is a load versus position curve for a wood test samplereinforced according to the present invention with three specific layersof composite reinforcing material;

[0026]FIG. 12 is a load versus position curve for a wood test samplereinforced according to the present invention with three specific layersof composite reinforcing material;

[0027]FIG. 13 is a load versus position curve for a wood test samplereinforced according to the present invention with five other specificlayers of composite reinforcing material; and

[0028]FIG. 14 is an H-tower in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] As can be seen from FIG. 1, a utility pole reinforced accordingto the present invention which is designated generally by the referencenumeral 10, comprises a wood core 11 wrapped with one or more layers ofa composite reinforcement material 12. Cross-arms 14 are mounted on thepole 10, and insulators 16 are mounted on the cross-arms to support oneor more lines 18 for the transmission or distribution of electricalpower.

[0030] As can best be seen from FIG. 2, the pole 10 has differentthicknesses of reinforcement at different sections along the length ofthe pole 10. The different thicknesses are due to differing numbers oflayers of reinforcement. The pole 10 includes an elongate wood body 20(FIGS. 3-5), which can be defined by a conventional, tapered woodutility pole. The thickest reinforcement on the pole, reinforcement 12a, extends from the bottom of the pole to a point which is at leastone-third of the height of the pole above the ground, when the pole isinstalled. The reason for this is that many utility pole failures occurat about one-third of their height above the ground. A middle section ofthe pole 10 is wrapped with composite reinforcement material 12 b havinga total thickness less than the thickness of the material 12 a on thebottom section of the pole. The top section of the pole is wrapped withcomposite reinforcement material 12 c having a total thickness less thanthe thickness of the material 12 b of the middle section. In FIG. 2, thedifference in the thickness of the reinforcement on the various sectionsof the pole is exaggerated for clarity of illustration. As analternative to the thicknesses just described, the middle section canhave a greater thickness of reinforcement than the other sections of thepole 10, if such an arrangement is called for by the loading on thepole. In addition, or as an alternative to the thickness arrangementsdescribed above, the individual layers can have different thicknessesfrom one another, and/or the directions in which the high tensilestrength filaments extend in the reinforcement can vary from one layerto another. Still other configurations of reinforcement can be used tosuit the loading to be imposed on the utility pole.

[0031] An end cap 22 made of composite material comprising high-strengthfilaments in a resin matrix is positioned at the top and bottom of thepole 10 to cover the top of the wood body 20. The cap 22 has a skirtextending for a short distance along the length of the pole 10, and theskirt is covered by the composite reinforcement material 12 covering thepole to help hold the cap on the pole.

[0032] As can be seen from FIGS. 2-4, the composite reinforcementmaterial 12 on the pole 10 comprises one or more layers of strips 26 and27 of the composite reinforcement material 12 wrapped helically aroundthe wood body 20. Typically, the strips are wrapped at a small helicalangle ‘a’ (FIG. 2) in the range of about 5° to about 30°, for whichapproximately 14.5° is typical. A first strip defining a first layer,such as strip 26, can be wrapped with the helical angle extending in onedirection relative to the horizontal and a next strip defining a secondlayer, such as the strip 28, can be wrapped with the helical angleextending in the opposite direction with respect to the horizontal. Athird strip 29 defining a third layer can be wrapped with a helicalangle in the same direction as the first layer, and so on. The strip cancomprise a large plurality of unidirectional parallel high tensilestrength filaments brought together in a resin matrix prior to curing ofthe resin but otherwise unattached. As an alternative, the filaments canbe stitched together. As another alternative, the strip can comprise twogroups of parallel filaments, the filaments of one group lying at anangle with respect to the filaments of the other group. Additionalgroups of filaments lying at still other angles can be included. Thegroups of filaments can be unattached, or can be stitched together orwoven together.

[0033] As can be appreciated from FIGS. 3 and 4, a wire 30 can beinstalled running the length of the pole 10, either in a notch 31 in thewood body 20, or simply on the outer surface of the wood body. In eithercase, the composite material 12 is wrapped over the wire 30 to protectit and secure it in place. The wire 30 can extend in a straight line,spiral around the pole, or have another configuration to function as anantenna. As an alternative, the wire 30 can also act as a groundingdevice to prevent stray currents from short arcing across the insulatorsmounted on the pole and to take any stray currents at the ground. Aplurality of wires 30 to serve a plurality of functions can be appliedto the pole.

[0034] As can be appreciated from FIGS. 5 and 7-9, the strips 26-28 ofcomposite reinforcement material 12 wrapped around the wood bodies 20,and additional strips, if used, such as strips S4 and S5 of the pole 10′of FIG. 5, are made from strips of parallel high tensile strengthnon-metallic filaments, such as glass fibers, having variousorientations. In each case, the fibers are arranged in parallel groupsand embedded in a matrix of a curable resin, such as an isophthalicpolyester resin, to form a composite reinforcement material having highstrength. Such resins are wet and viscous before curing and, preferably,the strips of high tensile strength filaments are saturated with theresin before the strips are wrapped helically around the wood body 20.When this is done, the resin causes the strips to adhere to the woodbody or to underlying strips. After the wood body 20 is wrapped, theresin is cured by conventional means. The cured resin makes thecomposite reinforcement material 12 impervious to the ingress ofmoisture.

[0035]FIG. 6 schematically shows a portion a type of strip 32, called a“matt”, which contains thousands of randomly oriented fibers orfilaments 34, such as glass fibers, either chopped or continuousstrands, adhered to one another. Such a strip is not nearly as strong asstrips having parallel filaments but is very conducive to absorbingresin, and the resin acts as a barrier to ultraviolet rays, moisture andother elements. Each line in FIG. 6 represents dozens of filaments.Actually, there are many more dozens of fibers 34 adhered together persquare inch than is indicated by FIG. 6, and the open spaces are muchsmaller than indicated. Such a strip 32 can be placed around the strips26-28 designed for high strength, as is shown in FIG. 4.

[0036]FIG. 7 shows a strip 36 made of bundles 38 of high tensilestrength filaments all oriented parallel to the length of the strip. Afew strands 40 of transverse thread are used to hold the longitudinalfilaments 38 together. Each bundle 38 of filaments indicated in FIG. 7contains hundreds or thousands of high-strength filaments of glass orother material.

[0037]FIG. 8 shows a strip 42 in which bundles 44 of longitudinalfilaments are woven with bundles 46 of transverse filaments. Again,there are at least hundreds of filaments in each bundle. About 80% ofthe filaments by weight can be longitudinal and about 20% of thefilaments by weight can be transverse (80/20), or about 50% can belongitudinal and about 50% transverse (50/50). Any relative amounts oflongitudinal and transverse filaments can be chosen in order to satisfythe strength requirements for the loads the pole will bear,[longitudinal for bending; circumferential for ?] Rather than beingwoven, the bundles 44 and 46 can be stitched together at right angles toone another. It can be particularly useful to choose the angles betweenthe bundles 44 and the length of the strip 42 and between the bundles 46and the length of the strip such that, when the strip 42 is wound aroundthe wood body 20 at a helical angle, the bundles 44 extend preciselycircumferentially around the wood body and the bundles 46 extendprecisely longitudinally, or vice versa.

[0038]FIG. 9 shows a strip 48 in which all of the high tensile strengthfilaments, which are in bundles 50, extend transverse to the length ofthe strip. Each bundle 50 contains hundreds of filaments. A fewlongitudinal threads 52 are used to hold the transverse bundles 50together.

[0039] At least when the strips of composite material defined by thehigh tensile strength filaments and the resin are cured, the strips havetremendous tensile strength in a direction parallel to the filaments.For each of the strips relied on to provide strength in one or morespecific directions, which, among the illustrated strips, includes thestrips of FIGS. 7-9, the filaments comprise about 70% by weight of thecomposite strip of filaments and resin and about 50% by volume, when thefilaments are glass filaments or fibers.

[0040] The various types of strips of high strength filaments can beused in various combinations, depending upon the properties desired. Ifit is desired to particularly increase the flexural strength andstiffness of the wood body 20, more layers of reinforcement formed bystrips having transverse filaments, such as the strip 48 of FIG. 9, areused. It can be appreciated that, when a strip of the material of FIG. 9is wrapped around an elongate wood body 20, the filaments will extendgenerally longitudinally of the wood body. The filaments are notprecisely longitudinal because of the angle of the helix along which thestrip is laid. However, since the angle ‘a’ of the helix is small (e.g.,14.5°), the tensile strength component of the filaments is almostentirely in the longitudinal direction of the wood body 20. Similarly,for the strips 36 of FIG. 7, the tensile strength component of thefilaments is almost entirely in the circumferential direction of thewood body 20, when the strip is wound helically around the wood body.

[0041] The following table shows the results of flexural bend tests on4″-diameter wood test poles (peeler poles, center heart). Each test polewas 40″ long and was place horizontally on supports spaced 28″ apart,with a force imposed by a slow moving machine element at the center ofthe 28″ span of the test pole between the supports. Thus, the force wasapplied transverse to the length of the pole by the machine element,which started from a position in engagement with the pole. TABLE 1 Loadin Lbs. Test Sample A B Average Bare (Control) 5,094 5,564 Bare(Control) 6,741 4,859 System 1 6,737 6,931 6,834 System 2 12,072 12,87812,475 System 3 13,613 13,841 13,727 System 4 7,975 8,178 8,076 System 517,663 19,150 18,406 System 6 19,342 20,556 19,949

[0042] With respect to the various systems of strips wrapped around thetest poles for which the test results are shown in Table 1, there arethree layers of strips used in Systems 1-3 and five layers used inSystems 4-6. For System 1, the innermost layer has randomly orientedfilaments, such as the strip 32 of FIG. 6, and the middle and outerlayers are made from strips in which all of the filaments arelongitudinal, such as the strips 36 of FIG. 7. In System 2, the innerlayer is made from strips comprising woven filaments of which 80% arelongitudinal and 20% are transverse, such as the strips 42 of FIG. 8.The middle and outer layers are made from strips in which all of thefilaments are longitudinal. For System 3, the innermost layer is madefrom a strip in which all of the filaments are transverse, such as thestrip 48 of FIG. 9, and the outer two layers are made from strips inwhich all of the filaments are longitudinal.

[0043] In System 4, the two innermost layers are made from strips inwhich the filaments are randomly oriented, and the other three layersare made from strips in which all of the filaments are longitudinal. InSystem 5, the two innermost layers are made from strips of wovenfilaments, of which 80% by weight are longitudinal and 20% by weight aretransverse. The other three layers are made from strips in which all ofthe filaments are longitudinal. In System 6, the two innermost layersare made from strips in which all of the filaments are transverse, andthe other three layers are made from strips in which all of thefilaments are longitudinal.

[0044]FIG. 10 is a graph of the vertical load in pounds on the bare testpole of Column A of Table 1 versus the position of the movable testmachine element in inches from the starting position. The force on thepole increased with the movement of the test machine element until 6,741lbs. was reached. After that point, the bare test pole broke and theload supporting ability of the pole dropped precipitously.

[0045]FIG. 11 is a load versus position graph for the test pole inColumn A of Table 1 with the System 3 reinforcement according to thepresent invention. It can be appreciated from FIG. 4 that the System 3reinforcement comprises an inner layer or wrapping of composite materialmade from a strip in which all of the filaments are transverse, as shownin FIG. 9. The middle and outer layers are made from strips in which allof the filaments are longitudinal, as shown in FIG. 7. As can be seenfrom FIG. 11, the load increased with increasing movement of the testmachine element to 13,613 lbs. At that point, there was a slightdecrease in the load, indicating a failure of the test pole, but thepole continued to bear a substantial load for about ⅓ of an inchadditional travel of the machine test element. Thus, there was somewarning before a complete failure of the test pole.

[0046] In the 5-layer reinforcement of the present invention accordingto System 6, FIG. 12 shows that the test pole in Column A of Table 1withstood 19,342 lbs., and there was considerable additional travel bythe machine test element before there was a sudden large drop in loadsupporting ability from about 17,500 lbs. to about 8,750 lbs. FIG. 13shows that, with the System 6 test pole of Column B, the ultimate loadbefore failure was 20,556 lbs., after which there was a substantialdecrease in load bearing ability to a lower plateau at about 12,400lbs., before a further drop in a load bearing ability with a substantialadditional movement of the machine test element.

[0047] As can be seen from FIG. 4, the outermost layer of compositereinforcement can be covered by a layer to protect the compositereinforcement layers from degradation by ultraviolet light andweathering. The barrier layer can comprise nylon, Reemay polyester orother polyester fibers in a strip which is would helically around andcovering the underlying composite reinforcement layers.

[0048] Although the present invention has been described herein inconnection with new utility poles, it is understood that the presentinvention can be used in connection with utility poles already inservice, whether or not they are damaged or weakened.

[0049] As can be seen from FIG. 14, an H-tower 58 can be constructed inaccordance with the present invention. The H-tower 58 includes twouprights 60, each having the same construction of the utility pole 10 ofFIGS. 1 and 2, including the composite reinforcement material 12. Theuprights 60 are connected by a crossbeam 62 that is also reinforced withthe composite reinforcement material 12. For the cross beam 62, thecomposite reinforcement material 12 typically has a uniform thicknessacross the entire crossbeam, and the crossbeam typically is not tapered.Of course, the thickness of composite reinforcement material 12 and thecross section of the crossbeam 62 can vary where conditions warrant.Both the uprights 60 and the crossbeam 62 are covered with the compositereinforcement 12 where they are joined to one another. Holes can bedrilled through the uprights 60 and the crossbeam 62, including thecomposite reinforcement material 12, to receive bolts for securing thecrossbeam to the uprights.

[0050] The present invention can also be used to reinforce wood coresfor use as marine pilings. Such marine pilings have many of the sameadvantages as reinforced utility poles according to the presentinvention. In addition, the wrapping of the wood cores with the stripsof composite reinforcement material helps prevent the resultantreinforced marine pilings from splitting when they are driven into theearth. The reinforcement protects the pilings from elements which tendto cause the pilings to deteriorate.

[0051] Having thus described the present invention and its preferredembodiments in detail, it will be readily apparent to those skilled inthe art that further modifications to the invention may be made withoutdeparting from the spirit and scope of the invention as presentlyclaimed.

What is claimed is:
 1. A reinforced wood pole comprising: an elongatedwood body defined solely by a core of a tree trunk; and at least onelayer of a strip of composite reinforcing material extending in a helixaround and in engagement with the wood body, the helix defining adjacentconvolutions in continuous contact the composite material comprisingparallel continuous high tensile strength fibers extending throughoutthe strip, and a resin matrix encapsulating the fibers to define thestrip.
 2. The reinforced wood pole of claim 1, wherein the fibers arenonmetallic.
 3. The reinforced wood pole of claim 1, wherein the polehas a top end and a 2 bottom end, and the reinforcing covers the entirepole, except the bottom end.
 4. The reinforced wood pole of claim 1,wherein the material of the wood body has a strength such that a woodbody having a diameter of 4 inches has insufficient strength in itselfto withstand a load of 7,000 pounds.
 5. The reinforced wood pole ofclaim 1, wherein the strip contains a first plurality of the fibersextending longitudinally in the strip and a second plurality of thefibers extending transversely in the strip, and said fibers of saidfirst and second pluralities are glass fibers and comprise approximately70% by weight of the strip.
 6. The reinforced wood pole of claim 5,wherein the strip extends helically around the pole at an angle of fromabout 5° to about 25°.
 7. The reinforced wood pole of claim 1, furthercomprising a plurality of layers of the strips.
 8. The reinforced woodpole of claim 7, wherein at least one of the number of layers of thestrips and the thickness of the strips decreases in a direction from thebottom of the pole to the top of the pole.
 9. The reinforced wood poleof claim 8, wherein the pole is secured in the ground, and the largestnumber of layers of the strips extends from the bottom of the pole tomore than one-third the height of the pole above ground.
 10. Thereinforced wood pole of claim 1, wherein all of the fibers of at leastone of said strips extend transversely in the strip and generallylongitudinally with respect to the elongate wood body.
 11. Thereinforced wood pole of claim 10, wherein the fibers which extendtransversely are glass fibers, and said glass fibers compriseapproximately 70% by weight of said at least one strip of compositereinforcement material.
 12. The reinforced wood pole of claim 10,comprising a plurality of said layers, wherein all of the fibers of atleast one of said strips extend longitudinally in the strip andgenerally circumferentially with respect to the elongate wood body. 13.The reinforced wood pole of claim 1, further comprising an electricallyconductive wire extending longitudinally under the composite reinforcingmaterial, from the top of the pole to the bottom of the pole.
 14. Thereinforced wood pole of claim 1, further comprising a barrier layer of amaterial defining a barrier against ultraviolet light, said barrierlayer substantially covering the composite reinforcing material.